Vehicle data: EDR, driver assistance and automated vehicles what the car recorded.

Almost every new car sold in Great Britain now carries systems that intervene in the driving task: automatic emergency braking, lane keeping, adaptive cruise control, and in a growing number of vehicles features that take over the driving for periods. These systems change two things about a collision. They change what happened, because the vehicle may have braked, steered or failed to do so independently of the driver. And they change what evidence exists, because the vehicle records much of it.

The evidence the vehicle keeps

• Event data recorders capture the seconds before and during an impact: speed, braking, throttle, steering, belt status and the activation of restraints. UN Regulation No. 160 sets out what a compliant recorder must store. The data is overwritten by later events, so preserving it early matters more than almost anything else.
• ADAS logs and telematics may record when a system issued a warning, intervened, or handed control back to the driver, and what the sensors detected.
• Dashcams and infotainment systems hold video, location and timing that can anchor the analysis to the fraction of a second.

The download itself is carried out by a qualified tool operator or obtained from the manufacturer; I do not carry out downloads. My work is the interpretation: knowing what each field means, how it was sampled, and where its limits lie. A recorded speed is not a measured speed; it is a wheel-speed signal processed by a controller, and the report treats it accordingly.

Assistance, automation and responsibility

In outline, the Automated and Electric Vehicles Act 2018 placed the insurer of an automated vehicle directly in line to compensate a victim when the vehicle was driving itself. The Automated Vehicles Act 2024 built the regulatory structure around that: authorised self-driving features, an authorised self-driving entity answerable for how the vehicle drives, and a “user-in-charge” who is not responsible for the dynamic driving task while a feature is engaged. Between full automation and no assistance sit the great majority of vehicles on the road today, where the driver remains responsible but the car may have acted.

The engineering question in each case is the same: what was the system designed to do in those conditions, what the recorded data show it did, and what interval the data show between any warning or intervention and the impact. The answer is reported with the same discipline as any other collision analysis, and with particular care about the limits of what the data proves.